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fwrite and decimal points

This is a discussion on fwrite and decimal points within the C++ Programming forums, part of the General Programming Boards category; Hi everyone, I have a program which takes the reading from a text box and saves it to a text ...

  1. #1
    Registered User
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    Feb 2010
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    128

    fwrite and decimal points

    Hi everyone,

    I have a program which takes the reading from a text box and saves it to a text file using the following code:

    Code:
    fopen_s(&pFile,"textfile.txt","w");
    fwrite (buf , 1 , sizeof(buf) , pFile ); //pFile and buf have been declared earlier (buf is the variable storing the user's unput to the text box).
    fclose (pFile);
    ...it seems to work OK when I put non-integers into buf, but when buf = an integer, the text file doesn't just have the number stored in it - it has this instead (for example when I put '3' into buf):

    3

    Why does it add that strange character on the end, and how can I stop it from doing that? Failing that, is there a way to always add a decimal point to a certain number of decimal places onto the end?

    Thanks.

  2. #2
    Registered User
    Join Date
    Jun 2005
    Posts
    5,851
    fwrite() is binary output. The output you are seeing therefore represents how an int with the value 3 is represented in computer memory. If you want text (human readable) output, use a function liike fprintf() to product your output.

    Incidentally, fopen_s() is not a standard way of opening a file. Apart from that, your code is idiomatic C, not C++.
    Salem likes this.
    Right 98% of the time, and don't care about the other 3%.

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